Seal for centrifugal pumps



Patented Nov. 9, 1948 Daniel Murphy; New Castle, Pa.

Application February 10, 1944, Serial No. 521,771

My invention relates to rotary pumps, and particularly to a device for sealing such pumps against the escape or infiltration of fluid between the rotating shaft of the pump and the pump body portion or wall through which the shaft extends.

The invention consists in certain new and useful improvements in the construction 01' rotary pumps, especially though not exclusively pumps that operate on fluids containing abrasive particles.

In an application for Letters Patent, Serial No. 477,703, filed March 2, 1943, now Patent No. 2,355,390, I have illustrated and described a pump that has enjoyed success in pumping slip" in the pottery industry, and it is in association with such pump that I shall describe my present invention, noting that the invention will find utility in many different forms of pumps operating on liquids or gases that may or may not carry abrasive particles.

In the accompanying drawings Figure 1 is a view, partly in side elevation and partly in vertical section, of a pump in which. in exemplary way, the invention has been embodied;

Figure 2 is a fragmentary view, showing partly in side elevation and partly in vertical section, the structure in which the invention is centered;

Figure 3 is-an "exploded viewfc'orresponding to Figure 2, and showing the'several elements of the essential structure moved apart for better visual consideration;

Figure 4 is a view similar to Figure 2, illus- 3 Claims. (Cl. 286-11) trating a modified form of the structure of the invention; and

Figure 5 is a sectionalview of one of the component parts of the modified structure.

The pump shown in the drawings comprises a body i, within which is formed the usual impeller chamber 2, and within the chamber a vaned impeller 3 is borne upon a rotary shaft 4. Under the influence of the rotating impeller,

' liquid is drawn from an intake passage 5 through the eye 8 of. the pump, and is delivered at the periphery of chamber 2 to adischarge passage I. When the pump is in operation, the pressure upon the delivery side, exerted upon the rotating impeller, holds the impeller under pressure in abutment upon the side wall on the right (as seen in Figure 1 of the pump chamber 2. This side. wall is advantageously iormed as, a removable,

and replaceable plate 8. v

The body I of the pump carries rigidly mounted upon it. a housing 9; and within the housing two bearings are formed, which carry rotatably 2 the shaft 4 of the impeller. The shaft 4 at its outer end (to theright, Figure 1) is adapted to be coupled to or otherwise brought into powertransrnitting connection with a suitable motor: and the mounting of the shaft insaid two spacedapart bearings is efiective to prevent whipping of the shaft when the pump is in operation.

One of the bearings includes an annular block ill, made in one piece with the housing 9 and the block l0, and with it the integral housing, is secured by set-screws Ii in a cylindrical seat [2, formed exteriorly upon the'body i of the pump. The other bearing consists of concentric rings i3 and I4 with rolling members, here shown to be balls l5, arranged in the raceTormedjor them by and between the rings. The inner ring l3 fits snugly upon the shaft l; the outer fits snugly within, but is adapted to slidelongitudi nally within, a bore i8, formed in the housing 9.

The bearing l3, i4, i5 abuts laterally upona ring ii, that, byset-screws i8, is secured to the shaft 4. The assembly of bearing and ring is held between two nuts [9 and 20, that, encircling the shaft 4 and movable freely along shaft 4, make screw-thread engagement with the bore IS. The housing 9 is made in the form of a cage, as shown,

to afford access to the inner nut I9, for adjust ing it.

Means are provided for bearings, and conventional means are here shown, consisting of lubricant cups 2! and 22, with ducts leading to the bearing surfaces.

It willbe seen that in the second bearingfthe bearing to' the right), and partipularly in the ring I1 and theco-operat'ing nuts I9 and 20, means are found for adjusting the shaft 4 longitudinally, in compensation 'for wear of the impeller 3 upon the plate 8. n

It is requisite that provision be made against withdrawal of lubricant from the bearings by the suction of the operating pump, and against ingress to the bearings, when the pump is at rest, of the liquid that is pumped, a supply of which remains standing in passageway 5. In the means to such end, and in the structural organization of such means with associate parts, the present invention exists.

In the seating of the bearing block it) in the body i of the pump an annular shaft-encircling plate 23 is, by the screws ll, clamped to place at the left-hand end (Figure 1) of the cylindrical seat 12. Thisannular plate is provided with a sleeve-like extension 24.; The extension may be integral with the plate itself, as shown. In the assembly it extends through the orifice in the lubricating the two pump wall formed for the passage of shaft 4. and in this .case into the passage 3. This extension is adapted for diminution of friction in the rotation of an adjacent body rotating in abutment Lubrication ducts are indicated at 4|, 42. The

annular plate is clamped with sealing eflect to the wall of the pump'casing, and its integral sleeve-like extension is the -immediate bearing member for the shaft; and, accordingly, I term the member 23, with its shaft-encompassing portion 24, the inner bearing and sealing member.,

In the assembly the plate 23 with its sleevelike extension 24 snugly encircles the shaft. The fit is, however, not so snug as to exert any re- 4 w 2 'sentially. the elastic body ofthe member 23 is 7 so organized in the assembly that it operates to press and maintain-the collar portion 23 insnug "running" contact with the face of the stationary portion 24, whereby a sealed engagement of the relatively rotatable portions 24 and 28 is maintained both when the pump is in operation and when itis idle. The member 28. by virtue of its physical nature. is adapted to maintain such sealed engagement even though a slight misalignment exists between the relatively rotatable parts.

The member 23 may take the formgoi a cylindrical sleeve, shown in Figure 3, and the collar straint upon the free turning of the shaft within the sleeve. The central bore throughv the bearing block I0 is of sufllciently larger diameter to form a packing gland for the shaft in its bearing block iii. In the cylindrical space formed by and between the shaft and the block to, and closed to the left by the plate 23 with its extension 24, are arranged bodies 30 of packing that; may in familiar manner be assembled in alternation with a lantern ring 3i. The packing will be of the usuaisort known as composition packing, as distinguished from rubber packing. and will typically consist of a strip or ring of asbestos filled with graphite: The gland is at its outer end closed by an annular block 32 with a sleevelike extension 33, that may be 'adjustably anchored in the'bearing block I0 by set-screws 34.

A sealingdevice cooperates with the shaftencom'passing portion 24 to prevent liquid from being sucked into the pump from the bearing structure (42, etc.) when the pump is'in operation, and to prevent liquid from draining from the pump into the bearing structure'when the pump is at rest. The sealing device comprises a collar portion 26' keyed, as at 21, to the shaft 4. The collar portion isthus made to rotate with the shaft, while being adapted to slide on the shaft to maintain, as presently will appear, snug contact with the selflubrlcating face of the stationary portion 24. S

Organized with the collar portion or member 26 is a tubular member 28 formed of flexible and elastic material that is resistant to deterioration under the eflects of the liquid being pumped and the lubricant used in the bearing structure. A synthetic rubber known on the market as "neomember 26 is provided with a circular slot 28athat in assembly receives the right-hand edge of the sleeve 28. At its left-hand end the sleeve is provided with a wall 28a having a circular opening 28b through which the impeller shaft 4 extends.

the sleeve is a collar member or disk 29 that is Cooperating with the left-hand end of recessed, as at 29a, to receive and support the left-hand end of the sleeve. The member 29 ineludes an orifice 29b that peripherally engages a flange portion 280 formed integrally'at the edge of the opening 28b in the sleeve, and this flange, when the parts are assembled on the shaft 4, extends throu h the orifice in the disk member 29, and is engaged by the right-hand end of a rigid sleeve that is 'slideable on the shaft. The proportions and dimensions of the 1 several elements of the sealing device are such that, when the elements are assembled in service positions, the body of the impeller, screwed into place on the threaded end of the shaft, forces the rigid sleeve-W-to the right; under the pressure of the right-hand edge of sleeve 50 against the flange portion 280. on the shaft-encircling sleeve member, 28, the flange portion is caused to bulge outward over the edge of the orifice in member 29, whereby, under the urging of the 'sleeve 50 pressed to the right on the shaft, the

disk member 28 also moves-to the right, affecting the outward bulging of the elastic, cylindricalbody of the member 28. As the impeller reaches fully screwed-on position,"the parts are arranged prene has been found to be a suitable material of which to form the member 28, but it will be understood that the invention is not predicated upon the selection of the particular material which may be used. Important characteristics of the member 28 are that it is mounted in shaft-encircling position; that at one end of its tubular or ringlike body it is'secured in sealed union to the collar portion 28, and at opposite end is secured in sealed union to the shaft, or to aportlon that is united to the shaft in such way that the effect is the same; that it (still reierring to the member 28) is adapted to. rota-teiri unison with the shaft and the collar portion 26; and that it is adapted to permit axiafmovement ofthe said collar portion on the shaft without breaking the sealed unions mentioned. "Preferably, if not ea- -member 28 provides adequate thrust to press as. they are shown in Figure 2. The outward bu.ging oi' the cylindrical body of the member .28 causes such body to press tightly against and to envelop the outer edge of the circular slot- 26a formed in collar member26, whereby a fluid-tightseal between the member'ZB and the right-hand end or the member 28 is provided. At the opposite end of-the member 28,- the pres-,

sure of the edge of rigid sleeve 50 against the' elastic flange 28c compresses the body of the flange and secures it in fluid-tight engagement with the surface of the shaft at a point between the'eollar member 26 and the impeller 3. i The rigid sleeve 50, disk member '29, flexible member 28, and collar member 28 all rotate in unison with the impeller shaft. While a helical spring may be provided within the member 28 on the shaft 4, "and compressed between members" 26 and 29, I have found that the inherent resilience or elasticity of the axially compressed body of the and hold the collar member 2Q in fluid-tight en: gagement with the face oi? the shaft-encompassing portion 24 carried by the pump body. Thus, a a seal ofthe sort desired is provided-a seal that remains liquid-tight and effective even though there be such misalignment of the parts that the rotating'collar member 28 has to wobble to main spring will engage the flange 280 of the member- 23 with the effect described.

I have described the flexible sealing member 28 to be in fluid-tight engagement with the impeller shaft 4, but it will be understood that the engagement with the shaft need not be immediate. It may be with a portion fixed in fluidtight position on the shaft, as illustrated in Figure 4. In this modification the sleeve and disk portions (50 and 29 of Figure 2) are formed as asingle element 290 secured upon the impeller shaft by means of an integral flange 500 clamped between the shoulder 60 on the shaft and the body of the impeller, with a compressible-gasket 6i interposed to insure a sealed union. The disk portion of the unit 299' includes a circular groove 29L similar to the groove 28a formed in the collar member 28. The flexible sealing sleeve is of the.v modified form (288) shown in Figure 5, and in the assembled structure the two ends of the sleeve 280 are secured and sealed to the members 289 and 288, respectively, after the manner that the right-hand end of the member 28 is secured and sealed to the collar member 28. Manifestly. the modified structure is effective to provide the desired seal between the rotary shaft 4 and the stationary body of the pump into which the shaft extends.

It will be perceived that I have sealed the passage of the pump shaft through the wall of the pump, against leakage, and by means of simple organization, and that I have provided bearing for the pump shaft that is easily assembled and separated, that, as in course of operation the wearing plate 8 and the impeller 3 are worn away, they may readily be removed and replaced; and that, as operation continues, the adjustment ing for gradual wearing away.

It may be noted that within the face of the stationary shaft-encompassing portion 24 of the structure, I provide a clearance or groove 92 that extends circumi'erentially oi the impeller shaft. This groove provides a recess in which lubricant may be retained.

Within the terms of the appended claims many variations and modifications are permissible. Indeed, it is contemplated that the seal of thisinvention may be used to seal the rotating shafts of machines and apparatus other than centrifugal pumps.

I claim as my invention:

1. A sealing device for a shaft comprising two collar portions arranged to be secured upon the shaft for rotation therewith and for movement relatively to one another axially of the shaft, at

'nuts l9 and 20 constitute means for compensat- M least one of said collar portions having an annular groove encompassing the shaft and opening towards, or facing, the other collar portion, a shaft-encompassing tubular sealing element arranged between said collar portions and in fluidtigh t engagement therewith, one end of said tu bular sealing element being positioned in said annular groove, and means for securing the two ,collar portions in juxtaposition, with the medial 10- body portion of said sealing element ibulged radially outward beyond said groove and pressed between said collar portions, whereby the body ma- :terial of the sealing element is compressed in fluid-tight engagement with the outer edge of said groove.

2. The structure of claim 1, wherein both of said collar portions include an annular groove, as defined. with the two ends of said tubular sealing element-severally positioned in such grooves, and with the body material of the outwardly bulged medial portion of said sealing element compressed in fluid-tight engagement with theouter edge of each of said annular grooves.

3. A sealing device for a shaft comprising two 4 collar portions arranged to be secured upon the shaft for rotation therewith and for movement relative to one another axially of the shaft, said collar portions having substantially flat opposed surfaces adjacent their peripheries, a shaft-encompassing tubular sealing element arranged between said collar portions and in fluid-tight en- REFERENCES orran v The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 864,448 Surth Dec. 25, 1900 1,897,280 Schwitzer Feb. 14, 1933 1,931,728 Fageol Oct. 24, 1933 2,027,505 Winkler Jan. 14, 1938 2,236,902 Haller Apr. 1, 1941 2,347,118 Matter Apr. 18, 1944 FOREIGN PATENTS Number Country Date 322,711 Great Britain 1929 458,262 Great Britain 1936 884,854

France 1929 

